1. Field of the Invention
This disclosure is directed to an organic light emitting diode display device that can increase color stability and assure a long life span.
2. Discussion of the Related Art
Recently, various types of flat display devices have been developed to reduce weight and volume which is a shortcoming of cathode ray tubes. These flat display devices include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and electroluminescence devices (ELs).
An organic light emitting diode (hereinafter, referred to as “OLED”) or electroluminescent device (EL) may include an anode electrode, a cathode electrode, and an organic light emitting material layer interposed between the anode electrode and the cathode electrode, wherein the anode electrode is typically made of a transparent conductive material such as ITO (Indium Tin Oxide), and the cathode electrode is typically made of a metal with a low work function such as Mg, Ca, Al, or an alloy thereof, In an OLED, positive charges (holes) and negative charges (electrons) are inserted into from the anode electrode and the cathode electrode, respectively, to the light emitting material layer, and recombined in the light emitting material layer thereby to form an excited state that may emit light.
An organic light emitting diode device has been developing in various structures. Among them, a white OLED generally has a red light emitting layer, a green light emitting layer, and a blue light emitting layer stacked. However, such a stack-structured white OLED has problems of short life span of the blue light emitting layer, low color stability caused by the short life span, and relatively high driving voltage. To overcome these problems, the number of layers may increase and the structure may be complicated, thus causing lowering in mass production.